Two-choice oviposition bioassays were conducted to test the stimulatory effect of walnut oil on oviposition by the Indianmeal moth, Plodia interpunctella Hübner (Lepidoptera: Pyralidae), a serious pest of stored-grains and processed foods in the United States. Specifically, with this ongoing study we intend to 1) determine the lowest dosage of walnut oil that will elicit a significant oviposition response by gravid females, and 2) characterize walnut oil and identify active fractions that elicit positive ovipositional response. Experimental arenas were plastic boxes (17 cm x 31 cm x 8 cm) containing two ‘food dishes’, each containing 10 g glass beads. Separate experiments were conducted using different concentrations of walnut oil: 0 mg, 0.05 mg, 0.1 mg, 0.25 mg, 0.50 mg, 0.75 mg, 1 mg, and 10 mg applied to glass beads; hexane-treated glass beads were control. Results show that walnut oil at concentrations of 0.05 mg and 0.25 mg per 10 g glass beads elicit significantly greater oviposition by females than the control. Fractionation of walnut oil by thin layer chromatography (TLC) and bioassay of the stimulatory effects of different fractions will be reported. Isolation and characterization of the active components from walnut oil may help devise traps or bait stations that divert oviposition from an economically important food commodity.